The dual role of RFX6 in directing ß cell development and insulin production.

RFX6 transcription factor is believed to play a central role in directing cell development of insulin-producing pancreatic islet. RFX6 homozygous mutations cause syndromic neonatal diabetes with hypoplastic pancreas. However, RFX6 heterozygous mutations cause maturity-onset diabetes of the young (MODY) with normal pancreas development. Here, we show that RFX6 may control islet cell development and insulin production in different manners. The rfx6 knockout zebrafish generated by CRISPR/Cas9 exhibited an overt diabetes phenotype. Pancreatic islet failed to form compact structures in the knockout fish. While endocrine pancreatic islet non-ß-cells were absent, insulin-producing ß-cells were present in the knockout fish. Although insulin mRNA level was normal in the ß-cells of the knockout fish, insulin protein level was decreased. High-throughput RNA sequencing (RNAseq) showed that differentially expressed genes were enriched in the translation term in islet ß-cells from the knockout fish. Chromatin immunoprecipitation sequencing (ChIPseq) of normally developed islet ß-cells from mice demonstrated that rfx6 interacted with translation initiation factors and controlled insulin translation. Our data indicate that Rfx6 may act as a transcription factor regulating the transcription of genes involved in mRNA translation, which may represent a new mechanism and treatment strategy for diseases.

Single-cell analyses identify distinct and intermediate states of zebrafish pancreatic islet development.

Pancreatic endocrine islets are vital for glucose homeostasis. However, the islet developmental trajectory and its regulatory network are not well understood. To define the features of these specification and differentiation processes, we isolated individual islet cells from TgBAC(neurod1:EGFP) transgenic zebrafish and analyzed islet developmental dynamics across four different embryonic stages using a single-cell RNA-seq strategy. We identified proliferative endocrine progenitors, which could be further categorized by different cell cycle phases with the G1/S subpopulation displaying a distinct differentiation potential. We identified endocrine precursors, a heterogeneous intermediate-state population consisting of lineage-primed alpha, beta and delta cells that were characterized by the expression of lineage-specific transcription factors and relatively low expression of terminally differentiation markers. The terminally differentiated alpha, beta, and delta cells displayed stage-dependent differentiation states, which were related to their functional maturation. Our data unveiled distinct states, events and molecular features during the islet developmental transition, and provided resources to comprehensively understand the lineage hierarchy of islet development at the single-cell level.

[Three novel genes BM390716, BI274487 and AA963863 involed in extracellular matrix metabolism of eight rat regenerating liver cell types].

To explore the roles of three novel genes BM390716, BI274487 and AA963863 and the correlation between them during liver regeneration of rats, eight kinds of liver cells were isolated using the combined percoll density gradient centrifugation and immunomagnetic bead method. Rat genome 230 2.0 array was used to detect the changes in expression of genes involved in metabolism of extracellular matrix and the novel genes in rat genome. Correlation between sequence homology, co-expression of the above genes and the physiological activities they involed in were analyzed using Microsoft Excel and BLAST software. The results showed that BM390716 was homologous to and co-expressed with pparα, BI274487 was homologous to and co-expressed with timp2, and AA963863 was homologous to and co-expressed with csgalnact1. It is predicted that BM390716, BI274487, and AA963863 were involved in extracellular matrix metabolism in eight types of rat regenerating liver cells.